The present invention relates to internal combustion engines and in particular to an improved throttle body for Otto cycle engines.
There is a continuing quest to improve the performance of internal combustion engines, both in terms of efficiency and power output. One essential element of internal combustion Otto cycle engines is a throttle body which controls the amount of air entering the engine. Engines produce power by converting chemical energy from reacting (i.e., burning) a mixture of liquid fuel and air into mechanical energy. While only about one third of the chemical energy is converted into mechanical energy, the amount of mechanical energy produced is roughly proportional to the amount of chemical energy released, which in turn is roughly proportional to the amount of air taken into the engine. Because the throttle body limits the amount of air taken into the engine, the throttle body also controls the amount of mechanical energy produced by the engine.
Various throttle bodies are known in the art, these include butterfly type throttle bodies and slide type throttle bodies. Butterfly type throttle bodies are common in many automobiles and are fairly simple, but include a shaft through the center of the throttle body throat which creates some restriction even when fully open. A plate rotated by the shaft to open and close the throttle body also restricts air flow through the throttle body.
Slide type throttle bodies require an extension of the throttle body housing to receive the slide as it opens and may become jammed due to dirt or gavel being captured between the slide and housing in some environments. Further, known butterfly type throttle bodies provide a very non-linear relationship between throttle position and air flow, especially upon initial opening of the throttle. Known fuel injection control units commonly use throttle position as an input and are programmed based on the behavior of the known butterfly type throttle bodies. Other throttle body types, for example, slide type throttle bodies, do not produce a similar non-linear relationship between throttle position and air flow, and difficulties arise when another throttle body type is substituted for a butterfly type throttle body. Unfortunately, the known fuel injection control units often allow only a narrow adjustment which is not adequate when another throttle body type is substituted for a butterfly type throttle body.